HF scientific 19998 Triple Validation Turbidimeter - 0-100 NTU - Manual (Page 14)

TVT 1 (5/02) 8
Rev. 2.6 (.pdf)
4-20 mA: The 4-20 mA output is driven by a 12 VDC power source and can drive
recorder loads up to 450 ohms. This 4-20 mA output is isolated from line power and earth
ground. Do not run 4-20 mA cables in the same conduit as power. Operation of these
alarms is covered in section 8.6 Setting the analog Output (O/P).
Ensure each instrument is not powered when connecting the 4-20 mA line. Connecting
an instrument while powered may cause the instrument to unnecessarily reset and
proceed through the power on checks.
4.0 Normal Operation
This process turbidimeter allows you to measure the turbidity of your process water on-
line. The turbidity of the process water is reported in Nephelometric Turbidity Units
(NTU). Readings above 10 NTU (100 NTU if range of 0-100 NTU is enabled) are
outside the range of this instrument.
During normal operation, the instrument will have the AUTO block highlighted with the
current scale displayed on the lower row of the display and the measured reading on the
upper row of the display (see illustration below).
In certain instances, during normal operation, the instrument will display a row of dashes
across the upper row of the display
This indicates that either the instrument is performing an auto-ranging function, or the
sample has a substantial amount of bubbles. If the dashes remain for an extended period
of time please ensure that the sample does not have a large amount of bubbles present; if
there are not bubbles present, please contact the HF scientific, inc. Technical Services
Department for further assistance and guidance.